From 65a5d12be1651a2c535c8b8f5e99a695d4036159 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 12 Dec 2009 19:24:51 +0000 Subject: [PATCH] Fix integer-to-bit-string conversions to handle the first fractional byte correctly when the output bit width is wider than the given integer by something other than a multiple of 8 bits. This has been wrong since I first wrote that code for 8.0 :-(. Kudos to Roman Kononov for being the first to notice, though I didn't use his patch. Per bug #5237. --- src/backend/utils/adt/varbit.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/src/backend/utils/adt/varbit.c b/src/backend/utils/adt/varbit.c index 23f8d2c9c2..3db46c690f 100644 --- a/src/backend/utils/adt/varbit.c +++ b/src/backend/utils/adt/varbit.c @@ -9,7 +9,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/adt/varbit.c,v 1.57 2008/01/01 19:45:53 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/utils/adt/varbit.c,v 1.57.2.1 2009/12/12 19:24:51 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1346,7 +1346,12 @@ bitfromint4(PG_FUNCTION_ARGS) /* store first fractional byte */ if (destbitsleft > srcbitsleft) { - *r++ = (bits8) ((a >> (srcbitsleft - 8)) & BITMASK); + int val = (int) (a >> (destbitsleft - 8)); + + /* Force sign-fill in case the compiler implements >> as zero-fill */ + if (a < 0) + val |= (-1) << (srcbitsleft + 8 - destbitsleft); + *r++ = (bits8) (val & BITMASK); destbitsleft -= 8; } /* Now srcbitsleft and destbitsleft are the same, need not track both */ @@ -1425,7 +1430,12 @@ bitfromint8(PG_FUNCTION_ARGS) /* store first fractional byte */ if (destbitsleft > srcbitsleft) { - *r++ = (bits8) ((a >> (srcbitsleft - 8)) & BITMASK); + int val = (int) (a >> (destbitsleft - 8)); + + /* Force sign-fill in case the compiler implements >> as zero-fill */ + if (a < 0) + val |= (-1) << (srcbitsleft + 8 - destbitsleft); + *r++ = (bits8) (val & BITMASK); destbitsleft -= 8; } /* Now srcbitsleft and destbitsleft are the same, need not track both */ -- GitLab